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An imaging apparatus includes a camera shake correction unit which uses a
coil and a magnet to move a movable portion including an image pickup
device relative to a fixed portion. A position detection section detects
the position of the movable portion. A setting section sets a resolving
power of the detection of the position by the position detection section
to a first or second resolving power which is a resolving power higher
than the first resolving power and at which an amount of deviation from a
target position is less than or equal to a pixel shift amount. A drive
control section performs pixel shifts to move the movable portion with
the second resolving power set by the setting section. A photography
control section causes the image pickup device to perform exposures by
timing of the pixel shifting and which composes images obtained by the
exposures.

Inventors:

NISHIHARA; Rintaro; (Tokyo, JP)

Applicant:

Name

City

State

Country

Type

OLYMPUS CORPORATION

Tokyo

JP

Assignee:

OLYMPUS CORPORATIONTokyoJP

Family ID:

1000001841933

Appl. No.:

15/060554

Filed:

March 3, 2016

Related U.S. Patent Documents

Application Number

Filing Date

Patent Number

PCT/JP2015/070711

Jul 21, 2015

15060554

Current U.S. Class:

1/1

Current CPC Class:

H04N 5/23287 20130101; H04N 5/23267 20130101

International Class:

H04N 5/232 20060101 H04N005/232

Foreign Application Data

Date

Code

Application Number

Feb 19, 2015

JP

2015-030903

Claims

1. An imaging apparatus comprising: a camera shake correction unit which
uses a coil and a magnet to move a movable portion including an image
pickup device relative to a fixed portion; a position detection section
which detects the position of the movable portion; a setting section
which sets a resolving power of the detection of the position by the
position detection section to a first resolving power or to a second
resolving power which is a resolving power higher than the first
resolving power and at which an amount of deviation from a target
position is less than or equal to a pixel shift amount; a drive control
section which performs pixel shifts to move the movable portion with the
second resolving power set by the setting section; and a photography
control section which causes the image pickup device to perform exposures
by timing of the pixel shifting and which composes images obtained by the
exposures.

2. The imaging apparatus according to claim 1, wherein a movement amount
of the movable portion is an amount corresponding to the pixel shift
amount, and the second resolving power is set to be a fraction of the
integer of the pixel shift amount.

3. The imaging apparatus according to claim 1, wherein the deviation
amount when the resolving power is set to the first resolving power is
equal to or more than three times the first resolving power, and the
deviation amount when the resolving power is set to the second resolving
power is equal to or more than three times the second resolving power.

4. The imaging apparatus according to claim 3, wherein the setting
section sets the resolving power of the detection of the position to the
second resolving power at a start of photography in a super-resolution
photography mode to acquire a super-resolution image.

5. The imaging apparatus according to claim 1, further comprising: a
camera shake detection section; and a determination section which
determines whether to correct a camera shake on the basis of an output
signal of the camera shake detection section, wherein the setting section
sets the resolving power of the detection of the position to the second
resolving power when the camera shake is not corrected.

6. The imaging apparatus according to claim 1, further comprising: a
camera shake detection section; and a target position setting section
which sets a movement amount of the movable portion on the basis of an
output signal the camera shake detection section and the pixel shift
amount, wherein the setting section sets the second resolving power so
that the amount of deviation from the target position set by the target
position setting section is less than or equal to the pixel shift amount.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation Application of PCT Application
No. PCT/JP2015/070711, filed Jul. 21, 2015 and based upon and claiming
the benefit of priority from the prior Japanese Patent Application No.
2015-030903, filed Feb. 19, 2015, the entire contents of both of which
are incorporated herein by reference.

[0005] There is known a camera shake correction unit which moves an image
pickup device to reduce an image blur generated in a taken image due to,
for example, a camera shake. In recent years, various suggestions have
been made to use such a function of moving the image pickup device by the
camera shake correction unit for purposes other than the camera shake
correction. For example, an imaging apparatus suggested in Jpn. Pat.
Appln. KOKAI Publication No. 2014-224940 corrects a camera shake and also
obtains an optical low pass filter effect by moving an image pickup
device and thereby changing the focus position of a subject image. The
imaging apparatus according to Jpn. Pat. Appln. KOKAI Publication No.
2014-224940 superimposes a modulation signal representing a minute
vibration component of the imaging apparatus on a position detection
signal from a position detection section which detects the position of
the imaging apparatus to generate a superimposition position signal, and
controls the position of the image pickup device on the basis of the
superimposition position signal so that the position of the image pickup
device can be controlled with a high degree of accuracy.

BRIEF SUMMARY OF THE INVENTION

[0006] The camera shake correction unit can also be used in
super-resolution photography. The super-resolution photography that uses
the camera shake correction unit is processing to perform multiple
exposures while shifting the image pickup device by a unit less than or
equal to a pixel pitch, and composes taken images obtained by the
multiple exposures to generate a super-resolution image. To perform such
super-resolution photography, it is necessary to control the position of
the image pickup device with an extremely high degree of accuracy.
However, to perform the super-resolution photography by the technique
according to Jpn. Pat. Appln. KOKAI Publication No. 2014-224940, it is
necessary to increase the accuracy of a position detection system.

[0007] The present invention has been made in view of the above-mentioned
circumstances, and an object of the present invention is to provide an
imaging apparatus capable of accurately controlling the position of a
camera shake correction unit to perform super-resolution photography
without using an accurate position detection element.

[0008] According to an aspect of the invention, there is provided an
imaging apparatus comprising: a camera shake correction unit which uses a
coil and a magnet to move a movable portion including an image pickup
device relative to a fixed portion; a position detection section which
detects the position of the movable portion; a setting section which sets
a resolving power of the detection of the position by the position
detection section to a first resolving power or to a second resolving
power which is a resolving power higher than the first resolving power
and at which an amount of deviation from a target position is less than
or equal to a pixel shift amount; a drive control section which, performs
pixel shifts to move the movable portion with the second resolving power
set by the setting section; and a photography control section which
causes the image pickup device to perform exposures by timing of the
pixel shifting and which composes images obtained by the exposures.

[0009] Advantages of the invention will be set forth in the description
which follows, and in part will be obvious from the description, or may
be learned by practice of the invention. The advantages of the invention
may be realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010] The accompanying drawings, which are incorporated in and constitute
a part of the specification, illustrate embodiments of the invention, and
together with the general description given above and the detailed
description of the embodiments given below, serve to explain the
principles of the invention.

[0011] FIG. 1 is a diagram showing a schematic configuration of an imaging
apparatus according to one embodiment of the present invention;

[0012] FIG. 2 shows a diagram of an assembly state of a camera shake
correction unit;

[0019] FIG. 9 is a graph showing the change of a position detection signal
when the movable portion is moved from a predetermined target position 1
to another target position 2 which is 0.5 pixel pitches away;

[0020] FIG. 10 is a graph showing the relation between the actual position
of the movable portion and the position detection signal when the
position detection signal from the hall elements is amplified at a still
image amplification factor;

[0021] FIG. 11 is a graph showing the relation between the actual position
of the movable portion and the position detection signal when the
position detection signal from the hall elements is amplified at a
super-resolution amplification factor;

[0026] Hereinafter, an embodiment of the present invention will be
described with reference to the drawings. FIG. 1 is a diagram showing a
schematic configuration of an imaging apparatus according to the present
embodiment. An imaging apparatus 1 shown in FIG. 1 includes an
interchangeable lens 100 and a body 200. The interchangeable lens 100 is
attached to the body 200 via a mount 202 provided in the body 200. When
the interchangeable lens 100 is attached to the body 200, the
interchangeable lens 100 and the body 200 are connected to each other to
be able to communicate with each other. The interchangeable lens 100 and
the body 200 cooperate to perform operations. The imaging apparatus 1
does not necessarily have to be a lens-interchangeable imaging apparatus.
For example, the imaging apparatus 1 may be a lens-integrated imaging
apparatus.

[0027] The interchangeable lens 100 includes an optical system 102. The
optical system 102 includes, for example, lenses and a diaphragm, and
brings a light flux from an unshown subject into a camera shake
correction unit 206 of the body 200. Although the optical system 102 in
FIG. 1 comprises the lenses, the optical system 102 may comprise one
lens. The optical system 102 may include a focus lens, or may be
configured as a zoom lens. In these cases, some of the lenses of the
optical system 102 are configured to be movable along a Z-direction which
is a direction along an optical axis O.

[0028] The body 200 includes a shutter 204, the camera shake correction
unit 206, a monitor 208, and an operation section 210.

[0029] The shutter 204 is, for example, a focal plane shutter disposed in
front of the camera shake correction unit 206 (on a positive side in the
Z-direction). When opened, the shutter 204 exposes the camera shake
correction unit 206. When closed, the shutter 204 shields the camera
shake correction unit 206.

[0030] The camera shake correction unit 206 generates an image of the
unshown subject by imaging the subject. The camera shake correction unit
206 moves a movable portion relative to a fixed portion by a voice coil
motor (VCM) that uses a coil and a magnet, and thereby corrects an image
blur that occurs in the taken image due to, for example, a camera shake.
The configuration of the camera shake correction unit 206 will be
described in detail later.

[0031] The monitor 208 is, for example, a liquid crystal display, and
displays an image based on the taken image generated in the camera shake
correction unit 206. The monitor 208 displays a menu screen for a user to
perform various settings of the imaging apparatus 1. The monitor 208 may
include a touch panel.

[0032] The operation section 210 is, for example, a release button. The
release button is a button for the user to instruct to start photography
by the imaging apparatus 1. The operation section 210 also includes
various operation portions in addition to the release button.

[0033] Next, the configuration of the camera shake correction unit 206 is
further described. FIG. 2 shows a diagram of an assembly state of the
camera shake correction unit 206. As shown in FIG. 2, the camera shake
correction unit 206 roughly comprises two fixed portions 301 and 302 and
a movable portion 303 disposed between the fixed portions 301 and 302. In
such a configuration, the camera shake correction unit 206 translates the
movable portion 303 in a plane (an X-direction and a Y-direction in FIG.
3) perpendicular to the optical axis O. The camera shake correction unit
206 also moves the movable portion 303 in a rotation direction around the
optical axis O.

[0034] First, the configuration regarding the movement of the movable
portion 303 in the camera shake correction unit 206 is described. FIG. 3
is an exploded perspective view of the camera shake correction unit 206.
As shown in FIG. 3, the fixed portion 301 disposed on the side of the
monitor 208 when seen from the movable portion 303 is a substantially
rectangular plate member and is fixed to the body 200. A magnet 3011 for
X-direction movement and a magnet 3012 for both X-direction and
Y-direction movement are respectively adhesively bonded to the outer
periphery of the fixed portion 301.

[0035] The magnet 3011 includes a first magnet which is in the shape of a
rectangular parallelepiped having its longitudinal direction in the
Y-direction and which is disposed so that its north pole faces toward the
movable portion 303 and a second magnet which is in the shape of a
rectangular parallelepiped having its length in the Y-direction that is
the longitudinal direction shorter than that of the first magnet and
which is disposed so that its south pole faces toward the movable portion
303. The second magnet of the fixed portion 301 is disposed adjacent to
the center of the right surface of the first magnet when seen from the
movable portion 303. The magnet 3012 includes a first magnet which is in
the shape of a rectangular parallelepiped having its longitudinal
direction in the Y-direction and which is disposed so that its north pole
faces toward the movable portion 303 and a second magnet which is in the
shape of a rectangular parallelepiped having its length in the
Y-direction shorter than that of the first magnet and having its
longitudinal direction in the X-direction and which is disposed so that
its south pole faces toward the movable portion 303. The second magnet is
disposed adjacent to the center of the right surface of the first magnet
when seen from the movable portion 303.

[0036] The magnet 3012 includes a third magnet which is in the shape of a
rectangular parallelepiped having its length in the X-direction that is
the longitudinal direction shorter than that of the second magnet and
which is disposed so that its north pole faces toward the movable portion
303. The third magnet is disposed on the lower surface of the second
magnet when seen from the movable portion 303. That is, the second magnet
that constitutes the magnet 3012 is combined with the first magnet
function as a magnet for X-direction movement, and is combined with the
third magnet to function as a magnet for Y-direction movement.

[0037] The fixed portion 302 disposed on the side of the shutter 204 when
seen from the movable portion 303 is a substantially L-shaped plate
member in which an opening for holding an image pickup device unit 3034
in the movable portion 303 is formed. A magnet 3021 for X-direction
movement and a magnet 3022 for both X-direction and Y-direction movement
are respectively adhesively bonded to the positions of the fixed portion
302 corresponding to the magnets 3011 and 3012 of the fixed portion 301.
The magnet 3021 has the same configuration as that of the magnet 3011,
and is disposed so that a different pole faces toward the magnet 3011.
The magnet 3022 has the same configuration as that of the magnet 3012,
and is disposed so that a different pole faces toward the magnet 3012.

[0038] The movable portion 303 is a substantially L-shaped plate member in
which an opening for mounting the image pickup device unit 3034 similar
to that of the fixed portion 302 is formed. Coils 3031 and 3032a for
X-direction movement and a coil 3032b for Y-direction movement are
disposed in the outer periphery of the movable portion 303. The coil 3031
is disposed at a position corresponding to the magnet 3011 and the magnet
3021 in a plate-shaped portion of the movable portion 303 extending in
the Y-direction. The coil 3032a is disposed at a position corresponding
to the first magnet and the second magnet of the magnet 3012 and the
magnet 3022 in the plate-shaped portion of the movable portion 303
extending in the Y-direction. The coil 3032b is disposed at a position
corresponding to the second magnet and the third magnet of the magnet
3012 and the magnet 3022 in the plate-shaped portion of the movable
portion 303 extending in the X-direction.

[0039] The image pickup device unit 3034 is mounted in the opening of the
movable portion 303. The image pickup device unit 3034 is a unit
including an image pickup device and its control circuit. The image
pickup device unit 3034 in the present embodiment includes the image
pickup device, a signal processing section, an A/D conversion section,
and an image processing section. The image pickup device images the
subject to generate an image signal regarding the subject. The signal
processing section subjects the image signal to analog processing such as
amplification processing. The A/D conversion section converts, into a
digital signal, the image signal processed in the signal processing
section. The image processing section subjects the image signal to image
processing to generate an image. The image processing section also
composes multiple images to generate a super-resolution image.

[0040] Two screw receivers 3015 are formed in the fixed portion 301, and
screw receiver holes 3025 are formed in the parts of the fixed portion
302 corresponding to the screw receivers 3015. The fixed portion 302 is
screwed so that the movable portion 303 is put between the fixed portion
301 and the fixed portion 302. In this instance, the coil 3031, the coils
3032a and 3032b, the magnet 3011, the magnet 3012, the magnet 3021, and
the magnet 3022 are out of contact to maintain a predetermined space
therebetween.

[0041] In such a configuration, if the application of electricity to one
of the coils 3031, 3032a, and 3032b is started, the movable portion 303
becomes afloat between the fixed portion 301 and the fixed portion 302.
The intensity of a drive electric current to apply electricity to the
coils 3031, 3032a, and 3032b in this state is controlled so that the
movable portion 303 is translated or rotated.

[0042] Next, the configuration regarding the position detection of the
movable portion 303 is described. Three position detection magnets 3013
are disposed in the fixed portion 301. One of the position detection
magnets 3013 is disposed in the upper part of the fixed portion 301. One
of the position detection magnets 3013 is disposed in the lower part of
the fixed portion 301. One of the position detection magnets 3013 is
disposed in the left part of the fixed portion 301. Moreover, as shown in
FIG. 4, three hall elements 3033 are provided at the positions on the
rear surface of the movable portion 303 corresponding to the position
detection magnets 3013. The position detection magnet 3013 provided in
the upper part of the fixed portion 301 and the hall element 3033
provided in the upper part of the movable portion 303 detect in pairs a
first displacement amount of the movable portion 303 in the X-direction
as a change amount of a magnetic field. The position detection magnet
3013 provided in the lower part of the fixed portion 301 and the hall
element 3033 provided in the lower part of the movable portion 303 detect
in pairs a second displacement amount of the movable portion 303 in the
X-direction as a change amount of the magnetic field. The position
detection magnet 3013 provided in the left part of the fixed portion 301
and the hall element 3033 provided in the left part of the movable
portion 303 detect in pairs a displacement amount of the movable portion
303 in the Y-direction as a change amount of the magnetic field. The
position of the movable portion 303 is detected by the difference of the
signals detected by the respective hall elements 3033.

[0043] FIG. 5 is a functional block diagram of the imaging apparatus 1
according to the present embodiment. The imaging apparatus 1 according to
the present embodiment performs a camera shake correction, normal still
image photography, and super-resolution photography. The camera shake
correction is processing to move the movable portion 303 to inhibit an
image blur that occurs in the image due to, for example, camera shake.
The normal still image photography is processing to perform one exposure
to obtain one taken image. The super-resolution photography is processing
to perform multiple exposures while shifting the movable portion 303 by a
pixel shift amount less than or equal to a pixel pitch, and composes
images obtained by the multiple exposures to obtain an image higher in
resolution than the original number of pixels of the image pickup device.

[0044] As shown in FIG. 5, the imaging apparatus 1 has, as functional
blocks, the camera shake correction unit 206, a position detection
section 402, a camera shake detection section 404, a photography control
section 406, a target position generation section 408, a subtraction
section 410, a drive control section 412, a determination section 414,
and a setting section. 416. Among these functional blocks, the
photography control section 406, the target position generation section
408, the subtraction section 410, the drive control section 412, the
determination section 414, and the setting section 416 comprise CPUs and
ASICs.

[0045] The position detection section 402 amplifies a position detection
signal from the hall elements 3033 of the camera shake correction unit
206, acquires the amplified position detection signal as a digital signal
to generate a present position signal indicating the position of the
movable portion 303, and outputs the generated present position signal to
the subtraction section 410.

[0046] The camera shake detection section 404 detects the amount of a
camera shake that has occurred in the body 200 of the imaging apparatus
1, and outputs a signal corresponding to the detected amount of the
camera shake. For example, the camera shake detection section 404 detects
a camera shake amount by an angular velocity sensor. The camera shake
detection section 404 also detects a camera shake amount from the
movement of the subject in the image generated in the camera shake
correction unit 206.

[0047] The photography control section 406 controls the driving of the
image pickup device of the camera shake correction unit 206. The
photography control section 406 also outputs, to the target position
generation section 408, a signal indicating whether to perform a camera
shake correction and/or super-resolution photography. When performing the
super-resolution photography, the photography control section 406
indicates, to the target position generation section 408, a signal
representing a predetermined target position for each exposure for
super-resolution photography. The photography control section 406 also
indicates, to the setting section 416, whether to perform the normal
still image photography or the super-resolution photography.

[0048] The target position generation section 408 generates a target
position signal indicating a target position to be the target of the
position control of the movable portion 303, and outputs the generated
target position signal to the subtraction section 410. When the camera
shake correction is performed, the target position generation section 408
generates a target position signal on the basis of a camera shake
correction signal based on a signal corresponding to the camera shake
amount from the camera shake detection section 404. When the
super-resolution photography is performed, the target position generation
section 408 generates a target position signal on the basis of a signal
indicating a target position from the photography control section 406.
When both the camera shake correction and the super-resolution
photography are performed, the target position generation section 408
combines (adds) the camera shake correction signal from the camera shake
detection section 404 and the signal corresponding to the target position
from the photography control section 406 to generate a target position
signal.

[0049] The subtraction section 410 outputs a deviation signal of the
target position signal generated in the target position generation
section 408 and the present position signal generated in the position
detection section 402 to the drive control section 412.

[0050] The drive control section 412 generates drive currents to be
supplied to the coils 3031, 3032a, and 3032b of the camera shake
correction unit 206 on the basis of the deviation signal output from the
subtraction section 410, and supplies the generated drive currents to the
coils 3031, 3032a, and 3032b and thereby moves the movable portion 303.

[0051] The determination section 414 determines whether a camera shake has
occurred in the body of the imaging apparatus 1 in accordance with the
camera shake amount detected in the camera shake detection section 404,
and outputs a signal indicating this determination result to the
photography control section 406 and the setting section 416.

[0052] The setting section 416 sets a resolving power of position
detection in the position detection section 402. When the normal still
image photography is performed, the setting section 416 sets the
resolving power of position detection in the position detection section
402 to a predetermined first resolving power. In contrast, when the
super-resolution photography is performed, the setting section 416 sets
the resolving power of position detection in the position detection
section 402 to a second resolving power which is determined in accordance
with the pixel pitch of the image pickup device.

[0053] The operation of the imaging apparatus 1 is described below. FIG. 6
is a flowchart showing the operation of the imaging apparatus 1. The
processing in FIG. 6 is started when the electric power supply of the
imaging apparatus 1 is turned on.

[0054] In step S101, the determination section 414 determines whether the
camera shake amount detected in the camera shake detection section 404 is
less than or equal to a standard value. This standard value is a value of
a camera shake amount such that an image blur is considered to have
occurred, and is previously stored in the determination section 414. When
it is determined in step S101 that the camera shake amount detected in
the camera shake detection section 404 is not less than or equal to the
standard value, the processing moves to step S102. When it is determined
instep S101 that the camera shake amount detected in the camera shake
detection section 404 is less than or equal to the standard value, the
processing moves to step S104.

[0055] In step S102, the setting section 416 sets the resolving power of
position detection in the position detection section 402 to a still image
resolving power which is the first resolving power. Here, the resolving
power in the present embodiment refers to a unit length [.mu.m/LSB]
indicated by the least significant bit of a signal loaded as digital data
from each of the hall elements 3033 of the camera shake correction unit
206. The still image resolving power is a resolving power in a normal
still image photography mode, and, for example, a resolving power stored
as a fixed value in the setting section 416 is used.

[0056] In step S103, the photography control section 406 turns on a camera
shake correction mode. The processing then moves to step S106. When it is
determined in step S101 that the camera shake amount is more than the
standard value, that is, that a great image blur has occurred, the camera
shake correction mode is turned on. As a result, the image blur that
occurs in the image is reduced.

[0057] In step S104, the setting section 416 sets the resolving power of
position detection in the position detection section 402 to a
super-resolution resolving power which is the second resolving power. The
super-resolution resolving power is a resolving power which is changed by
the pixel pitch of the image pickup device. The processing for setting
the super-resolution resolving power will be described in detail later.

[0058] In step S105, the photography control section 406 turns off the
camera shake correction mode. The processing then moves to step S106.
When it is determined in step S101 that the camera shake amount is not
more than the standard value, that is, that no image blur has occurred,
the camera shake correction mode is turned off.

[0059] In step S106, the photography control section 406 sets a
photography mode. The photography mode includes the normal still image
photography mode for performing the normal still image photography and a
super-resolution photography mode for performing the super-resolution
photography. One of the modes is set by, for example, a user's operation
on the menu screen displayed on the monitor 208.

[0060] In step S107, the photography control section 406 starts the
driving of the image pickup device of the camera shake correction unit
206 to perform a live-view display. The photography control section 406
then sequentially, displays, on the monitor 208, the images obtained in
the camera shake correction unit 206.

[0061] In step S108, the photography control section 406 determines
whether an instruction to start the normal still image photography has
been issued. That is, the photography control section 406 determines
whether the present photography mode is the normal still image
photography mode and whether an instruction to start photography has been
issued by the user. The instruction to start photography is an operation
of depressing the release button or a touch release operation. When it is
determined in step S108 that the instruction to start the normal still
image photography has been issued, the processing moves to step S109.
When it is determined in step S108 that the instruction to start the
normal still image photography has not been issued, the processing moves
to step S110.

[0062] In step S109, the photography control section 406 starts the
driving of the image pickup device of the camera shake correction unit
206 to perform the normal still image photography. The photography
control section 406 then records the image obtained in the camera shake
correction unit 206 in an unshown recording medium. The processing then
moves to step S116. Although not described, the camera shake correction
is performed together with the normal still image photography when the
camera shake correction mode is on.

[0063] In step S110, the photography control section 406 determines
whether an instruction to start the super-resolution photography has been
issued. That is, the photography control section 406 determines whether
the present photography mode is the super-resolution photography mode and
whether an instruction to start photography has been issued by the user.
As in the normal still image photography, the instruction to start
photography is the operation of depressing the release button or the
touch release operation. When it is determined in step S110 that the
instruction to start the super-resolution photography has been issued,
the processing moves to step S111. When it is determined in step S110
that the instruction to start the super-resolution photography has not
been issued, the processing moves to step S116.

[0064] In step S111, the setting section 416 sets the resolving power of
position detection in the position detection section 402 to the
super-resolution resolving power which is the second resolving power. The
processing for setting the super-resolution resolving power will be
described in detail later,

[0065] In step S112, the photography control section 406 determines
whether the camera shake correction mode is on at present. When it is
determined in step S112 that the camera shake correction mode is not on,
the processing moves to step S113. When it is determined in step S112
that the camera shake correction mode is on, the processing moves to step
S114.

[0066] In step S113, the photography control section 406 performs the
super-resolution photography. The processing of the super-resolution
resolving power will be described in detail later. After the end of the
super-resolution photography, the processing moves to step S115.

[0067] In step S114, the photography control section 406 performs the
super-resolution photography involving the camera shake correction. The
processing of the super-resolution photography involving the camera shake
correction will be described in detail later. After the end of the
super-resolution photography involving the camera shake correction, the
processing moves to step S115.

[0068] In step S115, the setting section 416 sets the resolving power of
position detection in the position detection section 402 to the still
image resolving power which is the first resolving power. The processing
then moves to step S116.

[0069] In step S116, the photography control section 406 determines
whether the electric power supply of the imaging apparatus 1 has been
turned off. When it is determined in step S116 that the electric power
supply of the imaging apparatus 1 has not been turned off, the processing
returns to step S101. When it is determined in step S116 that the
electric power supply of the imaging apparatus 1 has been turned off, the
processing in FIG. 6 ends.

[0070] Next, the processing for setting the super-resolution resolving
power is described. FIG. 7 is a flowchart showing the processing for
setting the super-resolution resolving power. The processing in FIG. 7
can be applied to both step S104 and step S111.

[0071] In step S201, the setting section 416 calculates a super-resolution
target resolving power. The calculation of the super-resolution target
resolving power is described below.

[0072] FIG. 8 shows the concept of pixel shifting according to the present
embodiment. In FIG. 8, the pixel pitch is an opening-inter-central
distance P between a pixel PIX1 and a pixel PIX2 that are adjacent to
each other. The pixel shifting is processing for shifting the position of
the movable portion 303 (image pickup device) by a pixel shift amount
within the pixel pitch. Thus, the pixel shift amount has a relation:
0<pixel shift amount<pixel pitch. For example, the pixel shifting
in which the pixel shift amount is a pixel pitch of 0.5 is processing for
shifting the pixel PIX1 and the pixel PIX2 by a pixel pitch of 0.5 in a
predetermined direction (rightward direction in FIG. 8) to produce a
pixel PIX1' and a pixel PIX2'.

[0073] When the position of the movable portion 303 is controlled by the
VCM, the amount of deviation of the movable portion 303 from the target
position is equal to or more than three times the resolving power of the
detection of the position by the position detection section 402. This is
because the movable portion 303 slightly vibrates due to the operating
principle of the VCM. The position deviates from the target position in
each of the positive and negative directions due to the vibration, so
that the amount of deviation of the movable portion 303 from the target
position is equal to or more than three times the resolving power of the
detection of the position by the position detection section 402.

[0074] FIG. 9 is a graph showing the change of the position detection
signal when the movable portion 303 is moved from a predetermined target
position 1 to another target position 2 which is 0.5 pixel pitch away.
Even if a position detection signal indicating that the position of the
movable portion 303 is the target position 1 is output, the actual
position of the movable portion 303 changes within a deviation amount 1
in FIG. 9 due to a deviation that occurs when the movable portion 303 is
moved by the VCM. If photography is performed in this state, an image
will be an image taken at any position within the deviation amount 1 from
the target position 1.

[0075] Similarly, even if a position detection signal indicating that the
position of the movable portion 303 is the target position 2 is output,
the actual position of the movable portion 303 changes within a deviation
amount 2 in FIG. 9. If photography is performed in this state, an image
will be an image taken at any position within the deviation amount 2 from
the target position 2.

[0076] When the deviation amount is greater than the pixel shift amount,
the positions of the movable portion 303 overlap as indicated in a part A
in FIG. 9, so that the actual position of the movable portion 303 maybe
reversed before and after the pixel shifting. If two exposures are
performed while the position of the movable portion 303 is reversed, an
image in which the image pickup device is located at the pixel PIX1' and
the pixel PIX2' is acquired in the first exposure, and an image in which
the image pickup device is located at the pixel PIX1 and the pixel PIX2
is acquired in the next exposure. If such images are composed, the
resolving power in a super-resolution image to be finally obtained
deteriorates.

[0077] Therefore, according to the present embodiment, the
super-resolution target resolving power (the resolving power of the
detection of the position by the position detection section 402 in the
super-resolution photography) is set so that the deviation amount may be
smaller than the pixel shift amount. Specifically, the super-resolution
resolving power is less than or equal to 1/3 of the pixel shift amount.
Thus, even if a deviation which is equal to or more than three times the
resolving power has been made from the target position of the movable
portion 303 as a result of the movement of the VCM, the actual position
of the movable portion 303 can be within the pixel pitch.

[0078] Furthermore, to finally move the movable portion 30 a correct
target position, it is necessary that the super-resolution target
resolving power be a fraction of the integer of the pixel shift amount.
Therefore, the setting section 416 sets the super-resolution resolving
power to be less than or equal to 1/3 of the pixel shift amount and to be
a fraction of the integer of the pixel shift amount. When the pixel shift
amount is a pixel pitch of 0.5, the setting section 416 sets, for
example, the super-resolution resolving power to 0.5 pixel pitch/3
[.mu.m/LSB]. Since there is a possibility that the deviation amount may
be more than three times the resolving power of the detection of the
position, the super-resolution resolving power is preferably a fraction
of the integer more than a pixel shift amount of 4.

[0079] Here, the explanation returns to FIG. 7. In step S202, the setting
section 416 respectively acquires a still image amplification factor and
a still image resolving power. The still image amplification factor is an
amplification factor of the position detection signal from the hall
elements 3033 by the position detection section 402 in the normal still
image photography mode. For example, an amplification factor stored in
the position detection section 402 as a fixed value is used.

[0080] In step S203, the setting section 416 calculates a super-resolution
amplification factor. The super-resolution amplification factor is an
amplification factor of the position detection signal from the hall
elements 3033 by the position detection section 402 in the
super-resolution photography mode. For example, the super-resolution
amplification factor is calculated as follows.

[0081] FIG. 10 is a graph showing the relation between the actual position
of the movable portion 303 and the position detection signal when the
position detection signal from the hall elements 3033 is amplified at the
still image amplification factor. In contrast, FIG. 11 is a graph showing
the relation between the actual position of the movable portion 303 and
the position detection signal when the position detection signal from the
hall elements 3033 is amplified at the super-resolution amplification
factor. As obvious from the above equation, the super-resolution
amplification factor is higher in value than the still image
amplification factor. If the position detection signal is amplified at
such a super-resolution amplification factor, the deviation amount can be
less than or equal to the pixel shift amount. As a result, a
super-resolution image that is high in resolution can be generated.

[0082] In step S204, the setting section 416 sets the calculated
super-resolution amplification factor in the position detection section
402. The processing in FIG. 7 then ends.

[0083] Next, the processing for the super-resolution photography is
described. FIG. 12 is a flowchart showing the processing for the
super-resolution photography.

[0084] The photography control section 406 performs loop processing for
repeating i times of exposures for super-resolution photography. First,
in step S301, the photography control section 406 indicates a target
position to the target position generation section 408 to move the
movable portion 303 of the camera shake correction unit 206 to the i-th
position. Accordingly, the target position generation section 408
generates a target position signal. The drive control section 412 then
moves the movable portion 303 to the target position in accordance with a
drive signal generated on the basis of a deviation signal of the target
position signal and the present position signal. Here, for example, a
preset fixed value is used for the target position of the
super-resolution photography. FIG. 13A and FIG. 13B show an example of
the target position of the super-resolution photography. In the example
of FIG. 13A, the movable portion 303 is moved 8 times in a quadrate shape
from an initial position 1 (corresponding to i=0). In this example, 8
target positions of i=0 to i=7 are set. In contrast, in the example of
FIG. 13B, an oblique movement of the movable portion 303 is also
included, and the movable portion 303 is moved 9 times from the initial
position 1. In this example, 9 target positions of i=0 to i=8 are set.
The settings in FIG. 13A and FIG. 13B are illustrative only. How to set
target positions is not particularly limited as long as upward, downward,
leftward, rightward, and oblique movements are combined.

[0085] In step S302, the photography control section 406 starts the
driving of the image pickup device of the camera shake correction unit
206. The photography control section 406 then records the image obtained
in the camera shake correction unit 206 in an unshown RAM. If i exposures
have not been finished, i is incremented, and the processing returns to
step S301 where the loop starts. If i exposures have been finished, the
processing moves to step S303.

[0086] In step S303, the image processing section of the camera shake
correction unit 206 composes i images obtained by the i exposures to
generate a super-resolution image. The processing in FIG. 12 then ends.

[0087] Next, the super-resolution photography involving the camera shake
correction is described. FIG. 14 is a flowchart showing the processing
for the super-resolution photography involving the camera shake
correction.

[0088] The photography control section 406 performs loop processing for
repeating i exposures for super-resolution photography. First, in step
S401, the photography control section 406 indicates a target position to
the target position generation section 408 to move the movable portion
303 of the camera shake correction unit 206 to the i-th position. In
contrast, when the camera shake correction mode is on, the camera shake
detection section 404 outputs a signal corresponding to a camera shake
amount to the target position generation section 408. The target position
generation section 408 combines the camera shake correction signal based
on the signal corresponding to the camera shake amount from the camera
shake detection section 404 and the signal corresponding to the target
position from the photography control section 406 to generate a target
position signal. The drive control section 412 then moves the movable
portion 303 to the target position in accordance with the drive signal
generated on the basis of the deviation signal of the target position
signal and the present position signal. The drive signal generated in
step S401 takes the camera shake amount into consideration. Therefore,
even if a camera shake or the like occurs and even if a high-precision
position detection element is not used, it is possible to correctly move
the movable portion 303 to the target position.

[0089] In step S402, the photography control section 406 starts the
driving of the image pickup device of the camera shake correction unit
206. The photography control section 406 then records the image obtained
in the camera shake correction unit 206 in the unshown RAM. If i
exposures have not been finished, i is incremented, and the processing
returns to step S401 where the loop starts. If i exposures have been
finished, the processing moves to step S403.

[0090] In step S403, the image processing section of the camera shake
correction unit 206 composes i images obtained by the i exposures to
generate a super-resolution image. The processing in FIG. 14 then ends.

[0091] As described above, according to the present embodiment, the
resolving power of the detection of the position by the position
detection section 402 in the super-resolution photography mode is a
resolving power such that the amount of deviation of the movable portion
303 from the target position is less than or equal to the pixel shift
amount. Thus, the accuracy of the position control for the movable
portion 303 can be improved, and each exposure in the super-resolution
photography mode can be performed in a situation where the position of
the movable portion 303 is an accurate position. Therefore, and even if a
high-precision position detection element is not used, it is possible to
generate a super-resolution image having high resolution.

[0092] While the present invention has been described above in connection
with the embodiment, it should be understood that the present invention
is not limited to the embodiment described above, and various
modifications and applications can be made within the spirit of the
present invention. For example, the above-described configuration of the
camera shake correction unit 206 is one example and can be suitably
changed. For example, the configuration of the VCM may be different. In
the embodiment described above, the super-resolution target resolving
power is calculated whenever the electric power supply of the imaging
apparatus 1 is turned on. The super-resolution target resolving power can
be set if the pixel pitch of the image pickup device is determined.
Therefore, the super-resolution target resolving power may be calculated
at the time of the manufacture of the imaging apparatus 1 and then stored
in the setting section 416, and subsequently, the stored super-resolution
target resolving power may be used.

[0093] Each process according to the embodiment described above may be
stored as a program executable by, for example, a CPU or the like as a
computer. Otherwise, each process can be stored and distributed in a
storage medium of an external storage device such as a memory card, a
magnetic disk, an optical disk, or a semiconductor memory. The CPU or the
like can then read the program stored in the storage medium of the
external storage device, and execute the above-described processes when
the operation of the CPU or the like is controlled by the read program.